1. VII Congresso Nazionale SISMES
Società Italiana delle Scienze Motorie e Sportive, Padova Ottobre 2015
Biomechanics characteristic of the patellofemoral instability
L. Spairani1,2,4, M. Schmid5 , F. Combi1,2,4, V. Toniato4, M.G. Cusella De Angelis1,2,3
 1Department of Public Health, Experimental and Forensic Medicine, Human Anatomy Unit, University of Pavia, Italy
2Laboratory of Functional Anatomy of Exercise, University of Pavia, Italy
3 Centre for Health Technologies (CHT), University of Pavia, Italy
4Rehabilitation Centre of Musculoskeletal Disorders, Torre d'isola (Pavia), Italy
5 Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Italy
Aim.
In normal condition, patellar stability is assured by both bone factors (patellar and trochlear morphology) and muscular-ligamentous factors (patellofemoral ligament, patellar tendon, quadriceps and vastus medialis oblique muscles). When this stability is not guaranteed, the phenomenon of the Patello-Femoral (PF) instability occurs producing knee anterior pain, Patello-Femoral Pain Syndrome and cartilage erosion [1]. In dynamic condition, the biomechanical analysis of forces and torque of knee joint allows to investigating the pathogenesis of the PF disturb which has a high influence in the context of sports. Fq
Methods.
Biomechanical studies, aimed to investigate the PF instability during the knee flexion-extension, analyze the different forces acting on the three anatomical planes [1-3]. In particular, the stabilizing force (Fs), defined on the sagittal plane, and the destabilizing force (Fd), defined on the coronal plane, are combined to compute the resultant force (R) on the transverse plane [2]. Fs and Fd, and consequently R, change in magnitude and direction in relation to the changes of the degree of knee joint flexion/extension. Moreover, based on the knee joint geometry a “triangle of security” has been defined [2].
F t
Piano SAGITTALE
Piano FRONTALE
Piano ORIZZONTALE
F d
F d Fq
F d
F s Ft
R 3
F s
F s
R 3
Results.
We have observed that with concomitant anatomical factors (misalignment, patellar and/or trochlear dysplasia, retraction of soft tissues) and depending on the degree of knee joint flexion/extension, the force R can fall on the triangle of security edges (lateral hyper-pressure) or outside it (subluxation or a luxation), producing PF instability. Moreover, the critical range of the knee joint flexion/extension, in which R tends to fall out of the triangle of stability, seems to be that between 20° and 30° of flexion. These values of knee joint flexion correspond to a posture frequently adopted in sports.
Conclusion.
The biomechanical analysis of the PF joint is important to understand the pathogenesis of the PF instability and to define new rehabilitation protocols.
References.
1.Fulkerson JP, Shea KP (1990) J Bone Joint Surg Am 72:
2.Laforgia R et al. (1994)J of Sports Trauma and Related Res16:
3.Farrokhi S et al. (2011) Osteoarthritis Cartilage 19:
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